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<h2><span class="refentrytitle">Function gatherv</span></h2>
<p>boost::mpi::gatherv — Similar to <a class="link" href="collectives_8hpp_1a37b487f942bdcb918a05c31e24f25573.html" title="Function gather">boost::mpi::gather</a> with the difference that the number of values to be send by non-root processes can vary. </p>
</div>
<h2 class="refsynopsisdiv-title">Synopsis</h2>
<div class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: &lt;<a class="link" href="../mpi/reference.html#doxygen.collectives_8hpp" title="Header &lt;boost/mpi/collectives.hpp&gt;">boost/mpi/collectives.hpp</a>&gt;

</span>
<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> T<span class="special">&gt;</span> 
  <span class="keyword">void</span> <span class="identifier">gatherv</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="classboost_1_1mpi_1_1communicator.html" title="Class communicator">communicator</a> <span class="special">&amp;</span> comm<span class="special">,</span> <span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special">&lt;</span> <span class="identifier">T</span> <span class="special">&gt;</span> <span class="special">&amp;</span> in_values<span class="special">,</span> 
               <span class="identifier">T</span> <span class="special">*</span> out_values<span class="special">,</span> <span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special">&lt;</span> <span class="keyword">int</span> <span class="special">&gt;</span> <span class="special">&amp;</span> sizes<span class="special">,</span> 
               <span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special">&lt;</span> <span class="keyword">int</span> <span class="special">&gt;</span> <span class="special">&amp;</span> displs<span class="special">,</span> <span class="keyword">int</span> root<span class="special">)</span><span class="special">;</span>
<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> T<span class="special">&gt;</span> 
  <span class="keyword">void</span> <span class="identifier">gatherv</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="classboost_1_1mpi_1_1communicator.html" title="Class communicator">communicator</a> <span class="special">&amp;</span> comm<span class="special">,</span> <span class="keyword">const</span> <span class="identifier">T</span> <span class="special">*</span> in_values<span class="special">,</span> <span class="keyword">int</span> in_size<span class="special">,</span> 
               <span class="identifier">T</span> <span class="special">*</span> out_values<span class="special">,</span> <span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special">&lt;</span> <span class="keyword">int</span> <span class="special">&gt;</span> <span class="special">&amp;</span> sizes<span class="special">,</span> 
               <span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special">&lt;</span> <span class="keyword">int</span> <span class="special">&gt;</span> <span class="special">&amp;</span> displs<span class="special">,</span> <span class="keyword">int</span> root<span class="special">)</span><span class="special">;</span>
<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> T<span class="special">&gt;</span> 
  <span class="keyword">void</span> <span class="identifier">gatherv</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="classboost_1_1mpi_1_1communicator.html" title="Class communicator">communicator</a> <span class="special">&amp;</span> comm<span class="special">,</span> <span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special">&lt;</span> <span class="identifier">T</span> <span class="special">&gt;</span> <span class="special">&amp;</span> in_values<span class="special">,</span> 
               <span class="keyword">int</span> root<span class="special">)</span><span class="special">;</span>
<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> T<span class="special">&gt;</span> 
  <span class="keyword">void</span> <span class="identifier">gatherv</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="classboost_1_1mpi_1_1communicator.html" title="Class communicator">communicator</a> <span class="special">&amp;</span> comm<span class="special">,</span> <span class="keyword">const</span> <span class="identifier">T</span> <span class="special">*</span> in_values<span class="special">,</span> <span class="keyword">int</span> in_size<span class="special">,</span> 
               <span class="keyword">int</span> root<span class="special">)</span><span class="special">;</span>
<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> T<span class="special">&gt;</span> 
  <span class="keyword">void</span> <span class="identifier">gatherv</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="classboost_1_1mpi_1_1communicator.html" title="Class communicator">communicator</a> <span class="special">&amp;</span> comm<span class="special">,</span> <span class="keyword">const</span> <span class="identifier">T</span> <span class="special">*</span> in_values<span class="special">,</span> <span class="keyword">int</span> in_size<span class="special">,</span> 
               <span class="identifier">T</span> <span class="special">*</span> out_values<span class="special">,</span> <span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special">&lt;</span> <span class="keyword">int</span> <span class="special">&gt;</span> <span class="special">&amp;</span> sizes<span class="special">,</span> <span class="keyword">int</span> root<span class="special">)</span><span class="special">;</span>
<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> T<span class="special">&gt;</span> 
  <span class="keyword">void</span> <span class="identifier">gatherv</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="classboost_1_1mpi_1_1communicator.html" title="Class communicator">communicator</a> <span class="special">&amp;</span> comm<span class="special">,</span> <span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special">&lt;</span> <span class="identifier">T</span> <span class="special">&gt;</span> <span class="special">&amp;</span> in_values<span class="special">,</span> 
               <span class="identifier">T</span> <span class="special">*</span> out_values<span class="special">,</span> <span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special">&lt;</span> <span class="keyword">int</span> <span class="special">&gt;</span> <span class="special">&amp;</span> sizes<span class="special">,</span> <span class="keyword">int</span> root<span class="special">)</span><span class="special">;</span></pre></div>
<div class="refsect1">
<a name="id-1.3.24.7.5.9.4"></a><h2>Description</h2>
<p>
</p>
<div class="variablelist"><table border="0" class="variablelist compact">
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<col align="left" valign="top">
<col>
</colgroup>
<tbody><tr>
<td><p><span class="term">Parameters:</span></p></td>
<td><div class="variablelist"><table border="0" class="variablelist compact">
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<col align="left" valign="top">
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</colgroup>
<tbody>
<tr>
<td><p><span class="term"><code class="computeroutput">comm</code></span></p></td>
<td><p>The communicator over which the gather will occur.</p></td>
</tr>
<tr>
<td><p><span class="term"><code class="computeroutput">in_values</code></span></p></td>
<td><p>The array of values to be transmitted by each process.</p></td>
</tr>
<tr>
<td><p><span class="term"><code class="computeroutput">out_values</code></span></p></td>
<td><p>A pointer to storage that will be populated with the values from each process. For non-root processes, this parameter may be omitted. If it is still provided, however, it will be unchanged.</p></td>
</tr>
<tr>
<td><p><span class="term"><code class="computeroutput">sizes</code></span></p></td>
<td><p>A vector containing the number of elements each non-root process will send.</p></td>
</tr>
<tr>
<td><p><span class="term"><code class="computeroutput">displs</code></span></p></td>
<td><p>A vector such that the i-th entry specifies the displacement (relative to <code class="computeroutput">out_values</code>) from which to take the ingoing data at the <code class="computeroutput">root</code> process. Overloaded versions for which <code class="computeroutput">displs</code> is omitted assume that the data is to be placed contiguously at the root process.</p></td>
</tr>
<tr>
<td><p><span class="term"><code class="computeroutput">root</code></span></p></td>
<td><p>The process ID number that will collect the values. This value must be the same on all processes. </p></td>
</tr>
</tbody>
</table></div></td>
</tr></tbody>
</table></div>
</div>
</div>
<div class="copyright-footer">Copyright © 2005-2007 Douglas Gregor,
      Matthias Troyer, Trustees of Indiana University<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at &lt;ulink url="http://www.boost.org/LICENSE_1_0.txt"&gt;
        http://www.boost.org/LICENSE_1_0.txt &lt;/ulink&gt;)
      </p>
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